LATEST DEVELOPMENTS IN SOILLESS GROWING ON GRODAN ROCKWOOL IN HOLLAND

Aside from his pure technical input he is the one to make economical decisions; (investments) to assure the profitability of his enterprise.

Faced with higher costs and a stabilising pricelevel for his products, the grower has to choose the right investments to improve quality as well as quantity.

"Missing the boat" means loss of profitability which can lead to the end of an enterprise.

In the beginning of the seventies the limitation on increase of yield was the soil factor. Due to diseases, too wet or too dry soils and too salty soils, the production level stabilised. Expensive and sometimes dangerous ways of disinfecting stopped the fall of production level but wasn't the solution to generate higher productions.

At the end of the seventies Grodan introduced Rockwool by successful trials in the Bleiswijk area.

Changing to a soilless crop on Grodan made it possible to avoid problems with soil-disease and to control the root environment (controlled water and nutrient supply).

Since 1976 a revolutionary development of soilless growing in Grodan took place.

This development resulted in an increase of production.

The developments of the last 5 years show that the growth in production hasn't reached it's limit. In 1986 some growers reached a tomato production of more than 50 kg/m2.

The difference in average price between Rockwool and soil in 1986, to be seen in Table 1, is due to the fact that the production on Rockwool starts earlier in comparison with soil.

Looking at the sectors propagation vegetables culture and floriculture, we'll try to describe those developments.

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